Department of Biochemistry and Molecular Biology and Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA.
Nucleic Acids Res. 2010 Mar;38(5):1623-35. doi: 10.1093/nar/gkp1088. Epub 2009 Dec 11.
Oligodeoxynucleotide libraries containing randomly incorporated bases are used to generate DNA aptamers by systematic evolution of ligands by exponential enrichment (SELEX). We predicted that combinatorial libraries with alternative base compositions might have innate properties different from the standard library containing equimolar A + C + G + T bases. In particular, we hypothesized that G-rich libraries would contain a higher proportion of quadruplex-forming sequences, which may impart desirable qualities, such as increased nuclease resistance and enhanced cellular uptake. Here, we report on 11 synthetic oligodeoxynucleotide libraries of various base combinations and lengths, with regard to their circular dichroism, stability in serum-containing medium, cellular uptake, protein binding and antiproliferative activity. Unexpectedly, we found that some G-rich libraries (composed of G + T or G + C nucleotides) strongly inhibited cancer cell growth while sparing non-malignant cells. These libraries had spectral features consistent with G-quadruplex formation, were significantly more stable in serum than inactive libraries and showed enhanced cellular uptake. Active libraries generally had strong protein binding, while the pattern of protein binding suggested that G/T and G/C libraries have distinct mechanisms of action. In conclusion, cancer-selective antiproliferative activity may be a general feature of certain G-rich oligodeoxynucleotides and is associated with quadruplex formation, nuclease resistance, efficient cellular uptake and protein binding.
含有随机掺入碱基的寡脱氧核苷酸文库被用于通过指数富集配体系统进化（SELEX）生成 DNA 适体。我们预测，具有替代碱基组成的组合文库可能具有与包含等摩尔 A+C+G+T 碱基的标准文库不同的固有特性。特别是，我们假设富含 G 的文库将包含更高比例的形成四链体的序列，这可能赋予理想的特性，例如增加核酸酶抗性和增强细胞摄取。在这里，我们报告了 11 种具有各种碱基组合和长度的合成寡脱氧核苷酸文库，涉及它们的圆二色性、在含血清培养基中的稳定性、细胞摄取、蛋白结合和抗增殖活性。出乎意料的是，我们发现一些富含 G 的文库（由 G+T 或 G+C 核苷酸组成）强烈抑制癌细胞生长，而对非恶性细胞则无影响。这些文库具有与 G-四链体形成一致的光谱特征，在血清中比非活性文库稳定得多，并且显示出增强的细胞摄取。活性文库通常具有强烈的蛋白结合，而蛋白结合的模式表明 G/T 和 G/C 文库具有不同的作用机制。总之，对癌细胞的选择性抗增殖活性可能是某些富含 G 的寡脱氧核苷酸的一般特征，与四链体形成、核酸酶抗性、有效细胞摄取和蛋白结合有关。
